An access network includes one or more radio network subsystems, each of which is a sub-network in the access network and comprises a radio network controller and one or more Node Bs (a Node B is also referred to as a base station). The radio network controller is a network element responsible for controlling radio resources in the access network; and the main functions of the Node B includes performing processing at the physical layer of an air interface, as well as some basic management operations for radio resources. When communication relationships are established between a user equipment (UE) and a plurality of radio network controllers, different radio network controllers are connected via Iur interfaces, where a radio network controller responsible for communication between the UE and a core network is referred to as a serving radio network controller, and a radio network controller responsible for signaling and data transmission for the UE but not responsible for the communication between the UE and the core network is referred to as a drift radio network controller.
During the optimization of the techniques in present systems, the high speed uplink packet access technique, into which a high order modulation mode of 16QAM has been introduced so far, has been continuously evolving to improve the quality of users' experiences and the throughput of the system. The introduction of the high order modulation mode of 16QAM means that data can be transmitted by users at a higher rate and accordingly higher power is required to meet the requirement of service quality, which leads to great change in the method of uplink power control and how the Node B determines a grant.
There are two methods for the Node B to determine a grant, one is absolute grant, and the other is relative grant. Regardless of whether it is absolute grant or relative grant, it is actually that the Node B indicates a usable power resource (which may correspond to an absolute grant value) to the UE based on factors such as allocable resources in the cell, the user's channel quality indication, and required data size, and then informs the UE of the usable power resource through a index or by way of relative rising/lowering. The UE determines a rate at which data can be transmitted based on the power resource. It can be seen that the Node B needs to know explicitly a corresponding relationship between the index and the absolute grant value to ensure that the UE may determine the rate at which data can be transmitted within an upper limit of the power that the Node B expects the UE to transmit.
After 16QAM is introduced, the previous corresponding relationships between indexes and grant values (powers) are no longer able to meet the requirement, therefore the 3GPP (the 3rd generation partnership project) protocol has introduced new tables of corresponding relationships between indexes and grant values for absolute grant and relative grant respectively, i.e., higher grant values have been introduced to meet the requirement of higher rate. At present, there are two absolute grant mapping relationship tables specified in the protocol for the E-AGCH to use, as shown in tables 1 and 2, where the absolute grant value mapping table shown in table 1 is the table of the relationships between absolute grant values and indexes before 16QAM is introduced, and the absolute grant value self-adapting mapping table shown in table 2 is the table of the relationships between absolute grant values and indexes after 16QAM is introduced. Two items of index numbers and absolute grant values are included in the content of each table.
TABLE 1Absolute grant value mapping tableAbsolute Grant ValueIndex(168/15)2 × 631(150/15)2 × 630(168/15)2 × 429(150/15)2 × 428(134/15)2 × 427(119/15)2 × 426(150/15)2 × 225(95/15)2 × 424(168/15)223(150/15)222(134/15)221(119/15)220(106/15)219(95/15)218(84/15)217(75/15)216(67/15)215(60/15)214(53/15)213(47/15)212(42/15)211(38/15)210(34/15)29(30/15)28(27/15)27(24/15)26(19/15)25(15/15)24(11/15)23(7/15)22ZERO_GRANT*1INACTIVE*0
TABLE 2Absolute grant value self-adapting mapping tableAbsolute Grant ValueIndex(377/15)2 × 431(237/15)2 × 630(168/15)2 × 629(150/15)2 × 628(168/15)2 × 427(150/15)2 × 426(134/15)2 × 425(119/15)2 × 424(150/15)2 × 223(95/15)2 × 422(168/15)221(150/15)220(134/15)219(119/15)218(106/15)217(95/15)216(84/15)215(75/15)214(67/15)213(60/15)212(53/15)211(47/15)210(42/15)29(38/15)28(34/15)27(30/15)26(27/15)25(24/15)24(19/15)23(15/15)22ZERO_GRANT*1INACTIVE*0
However, at present, the 3GPP protocol serving radio network controller only informs the UE of which absolute grant value mapping table to be used via the air interface, but does not inform the drift radio network controller via the Iur interface, and there is no explicit specification, as a result, grant values corresponding to the Node B and the UE are acquired from different tables of relationships between grant values and indexes, which leads to inconsistency between allocation and use of the power resource by them, and ultimately results in reduction of the system throughput due to overload or the UE insufficiently using the usable power resource.